Scientists find climate change tipping point for tropical forests

Forests in the tropics will be resilient to global warming as long as we stop temperatures rising 2C above pre-industrial levels, research has found.

21 May, 2020 18:00

Tropical forests can still act as effective carbon sponges in a warmer world, research across three continents has found, but only if nations act quickly to cut greenhouse gas emissions.

A team of researchers coordinated by the University of Leeds found rainforests can continue to absorb huge volumes of carbon if global warming remains less than 2C (35.6F) above pre-industrial levels.

Increases above a threshold of 32C (89.6F) average daytime temperatures during the warmest month of the year was the point at which tropical forests’ ability to store carbon starts to diminish.

Currently 25% of tropical rainforests are above this 32C threshold, and store less carbon than their cooler counterparts.

Lead author Dr Martin Sullivan told the PA news agency that under the a 2C scenario of global warming, tropical forests will be 2.4C (36.3F) hotter than today due to the fact some regions warm faster than others.

This would push three-quarters of tropical forests above the 32C “safety zone”, and begin the rapid release of carbon back into the atmosphere.

The world’s tropical forests store an estimated 25 years worth of fossil fuel emissions in their trees.

Every degree of further warming above the 32C threshold releases four times as much carbon as would have been released compared to below this point, the research found.

Fragmentation of these forests through fire and logging could also impede tree species’ ability to adapt to a changing world, even if warming is kept below 2C.

Dr Sullivan, from the University of Leeds and Manchester Metropolitan University, said: “Our analysis reveals that up to a certain point of heating tropical forests are surprisingly resistant to small temperature differences.

“If we limit climate change they can continue to store a large amount of carbon in a warmer world.